The present invention relates to automated data storage libraries for storing and retrieving cartridges with data storage media therein, for use by data processing apparatus having access to such libraries.
Automated data storage libraries provide a data storage environment in which large quantities of data are distributed between a plurality of discrete data storage elements, such as magnetic tape or optical disk cartridges, which are placed in addressable storage cell locations arranged in one or more storage cell banks. The storage elements are accessed using positionable cartridge picker mechanisms which may include one or more selectively operable cartridge grippers.
In order to transport a data storage element between storage cell locations, one of which may contain a data read/write unit in communication with a host data processing system, a picker mechanism is first positioned at a source storage cell containing a data storage element to be retrieved. A gripper is activated to engage the storage element and retract it from the storage cell. The picker mechanism is then positioned at a destination cell and the gripper is again activated to insert the storage element in the storage cell and release it.
Data storage libraries have been proposed in which single direction pickers are used to access columns of cartridge magazines from a single side. The storage cartridges are picked at one end that is opposite to the cartridge opening or shuttle door. This picker arrangement has the capability to reach only one cartridge at a time from one fixed position. Applicant has proposed a data storage library using a pass through picker that can reach multiple cartridges on opposing sides of the picker (180 degree picking) without changing its position, which opens the possibility of extendable library architectures involving a combination of dual-opening storage cells and duel cell pickers.
It is submitted that further advantage could be derived from a data storage library that is extendable by its capability to provide 180 degree picking, yet which also has the ability to function as an end picker in order to serve additional storage cells without having to be repositioned. Adding repositioning capability to this arrangement would permit access to still more storage cell configurations. What is required is a system of reduced complexity and cost in which configuration flexibility is maximized and data storage and retrieval times are effectively minimized.